1. Field of the Invention
The present invention relates to a substituted polyvinyl acetal resin, to use thereof as an additive for promoting adhesion of acrylate or methacrylate ester based products to polyester plastic substrates, and to a method of producing such an additive. The invention also relates to an adhesive composition for use on polyester plastic substrates.
2. Description of the Related Art
Adhesion of acrylate or methacrylate compositions to plastic substrates has long been a problem. Many approaches to overcoming this problem have been undertaken. The first approach concerns the alteration or modification of the plastic surface prior to application of the composition by, for example, etching with, for example, haloacids (U.S. Pat. No. 2,801,447, L. E. Wolinski), flame treatment (E. F. Buchel, British Plastics 37 (1964) p142), corona discharge treatment (J. C. Von der Heide & H. L. Wilson, Modern Plastics 38 9 (1961) p199), solvent treatments (R. M. Herman, Modern Plastics 39 5 (1962) p153) and high energy radiation treatments (Practising Polymer Surface Chemistry. D. Dwight, Chemtech. (March 1982) p166). Other approaches include the use of additives, for example, polyvinylacetate has been proposed for use as an additive with ultraviolet light curing acrylate or methacrylate compositions in U.S. Pat. No. 3996394, E. B. Harris.